# How to test internal resistance on small lithium polymer cell?

I'm coming from a computer science background, and will be writing some software to automate battery testing. I have background in math, but little to none in physics or electronics. Please consider this in your answers.

That said, how would I go about testing the internal resistance of a small lithium polymer cell by hand?

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Measure open-circuit voltage $V_{oc}$, then load the battery with resistor $R_{load}$ and measure voltage $V_{loaded}$.
$$R_{in} = R_{load} \cdot \frac{V_{oc}-V_{loaded}}{V_{loaded}}$$